Flexible corrugated wall.



PATENTED MAY 12, 1968.

w. M. FULTON. FLEXIBLE CORRUGATED WALL.

APPLICATION FILED MAY 29, 1907.

I w- P 9 amnul'oz advantages, I have also enabled the Wall to connecting members,'eaoh ofsaid lateral "UNITED STATES rgrnnr ornron.

WESTON M. FULTON, OF KNOXVILLE, TENNESSEE, ASSIGNOR TO THE FULTON COMPANY, OF KNOXVILLE, TENNESSEE, A CORPORATION OFMAINE.

FLExiBLE connnea'rnn WALL.

Specification 0! Letters Patent.

Patented May 12, .1908.

To all whom 'it may concern:

Be it known that I, WnsToN M. FULTON, of Knoxville, Tennessee, have invented a new and useful Improvement in Flexible Corrugated Walls, which improvement is fully set forth in the following specification.

This invention relates to improvements in flexible corrugated tubular metal walls for collapsible and expansible vessels,-and has for its object to provide walls of the class re ferred to in which the burden of compression and expansion willbe more easily distributed to all portions of the wall, thereby relieving the strains at the curved portions of the corrugations. i

i .It has heretofore been proposed, as in applicant's Patent No. 729,926, to connect the outer and inner curves of the corrugations with lateral cbrrugated portions so as to stiffen said portions and prevent them from yielding except in the desired direction.

, In the resent invention I have aimed to simplify tlie above construction of the corrugations while retaining the advantages of a; very flexible Wall,-and particularly I have relieved the curved portions'of' the corrugations from'beniling strains, and have enabled the lateral portions to largely contribute to the movement of expansion and contraction of the Wall. By thus simplifying the form of the corrugation .witho'ut sacrificing any of the be more easily made, and thereby cheapened its construction. i

My invention chiefly resides in so construct ing the lateral portions of the corrugations as to enable them to contribute largely to the movement of expansion and contraction'of the wall, and thereby reduce the bending motion in the curved portions, and broadly stated, consists in providing a flexible corrugated wall, the same-consisting of alternate concave and convex members and lateral connecting members containing a'portion lying in a lane approximately normal to the axis of the wall, and another portion lyin in a plane making an angle with said norma portions, whereby the strains at the curved portions of the corrugations may be greatly relieved and the movement of contraction and expansion may take place in the lateral portions as well as in the bends.

In order that the invention may be more readily understood, reference .will be had to claims for that purpose.

' Figure 1 is a vertical centralsection of a corrugated wall, showing the corrugations in normal position; Fig. 2 is an enlarged fragmentary view showing the wall in section, the dotted line positions showing the wall when expanded and collapsed; Fig. 3 is a similar view to Fig. 2, but showing a certain portion of the wall omitted; and Figs. 4to 9 inclusive are more or less diagrammatic vielvlvs showing the method of making the wa Referring to Fig. 1, the flexible tubular wall l'is made of sheet metal such as steel or brass, and is provided with a series of corrugations which are made up of curved portions radii 0 a, and 0 as indicated. in Fig. 1. These curved portions are connected in se- '15 3, 4- included apzproximately "between the ries-by a lateral portion extendingbe-tween the points a and I). These lateral curve-connectin portions consist of flat portions a c, b d, su stantially normal to the axis of the tubular wall, together with ortions c d which make obtuse angles wit the normal portions a c and (Z I) and are'capable of bending through a greater angle than the-por- 'tions in immediateproximity to the curved portions. The distance between the-alternate concave and convex portions measured between parallel tangents to the curves is alline section shows a single corrugation of a tubular wall in normal osition, neither-collapsed nor extended. he upper dotted line osition shows the Wall expanded and the ower dotted line position shows the wall collapsed. The bend or curve 3 is on the inner curved portion of the tubular wall, and for the sake of clearness is assumed to be stationary, while the outer curved portion 4 moves in the direction of the axis of the tubular wall. Let'it be assumed that an expanding force has been ap lied to the tubular corrugated wall of a va ue within the working limits for which the wall is intended. The

' When the wall expandsthe lateral portion measurements.

I I connected with 1t.

connecting the bends lengthens, and when the wall collapses-the lateral portion is placed under a com ression force, and a reverse action takes p ace in the portions 0. c, c d, and d b to shorten-the same. A certain amount of the expanding movement is there y caused. to take place in the lateral portions themselves which connect the curved portions, thus relieving the curved portions of a part of their burden. It is possible for the tubular wall as thus constructed to expand and to collapse to a certainextent without any change whatever occurring in the curved' portions, as has been determined by careful In this case it is evident that the bending strain is confined to the ortion 0 d and the lateral portions a c an d b In actual practice, however, the-bending strain is not confined en,- tirely to portion 0 d, for when the wall-is in actual use it is generally required to expand and collapse through a considerable range, and then thebendin'g strain extends to the curved portions. The relative share of the bending strains sustained by the different portions of my improved wall will,depend upon the range throu h which the wall is expanded and colla se Whenthe range of expanding and co apsing is small, the strain is confined almost entirely to the portion a d, butwhen the range is great the curved portions 3, 4 sustain the larger part of the strain. Under ordinary circumstances, the strain is fairly well distributed between the curved to the lateral portion-relieves a wall of sixteen corrugations of one-half inch in movement, which amounts to a decided gain in the life of the curved portions.

To illustrate one method of making my improved wall, and the one which I prefer to employ, reference is had to Figs. 4 to 9. A

Sr. No. 366,207, hled thin metal tube is provided with alternate broad outward and narrow inward corrugations, Fig. 9, preferably formed in the manner described in my 00- ending application, pril 3, 1907. The broad inward corrugations 5 are then deepened and narrowed by subjection to rol ing pressure between a die roll 6 and a matrix roll 7, the flanges of which latter are too shallow to reach to the full depth of the corrugations. The action of these shaping rolls on the metal whereb they give to the lateral portion the desire form, will be more readily understood by a consideration of Figs. 5, 6,

7 and 8, which showa single corrugation on an enlarged scale as it is being formed, Fig.

, 5 showing diagrammatically portions of a pair of sha ing rolls 8 and 9, the roll 8 constituting a is and the lower roll 9 a matrix. The flanges .10 of the matrix roll 9 are shorter than the depth of the corrugations in the tube to be operated on, to thereby revent stretching of the connecting latera portionwhen the die roll enters the depression in the matrix roll. The corrugations to be; reshaped are the'broad corrugations 11 one of which is shown, Fig. 5, in position betweenthe rolls 8 and 9 just prior to the application of pressure. At the first ap lication of' rolling pressure to force the ben into the matrix roll 9, the radius of curvature of the bendshortens and the lateral portions connectingthe alternat'e bends 3, 4 begin to collapse against the sides of the die roll 8, and they take the position shown in Fig. 6. Continued action of the shaping rolls begins to straighten the side and terminal portions of the bend 3. and forces the lateral portionsfurther into contact with the sides of the die roll 8, as indicated in Fig. 7. Further rolling com letes the flattening of the sides of, the bent into the straight portions a c', Fig. 8. The portion marked 0 (1 corresponding to portion 0 d of Figs. 1 and 2 is under a strain when the rolling operationv is completed and endeavors to relieve itself by springing inward, but is prevented from doing so by the die roll 8 as soon, however, as die roll 8 is withdrawn from the corrugation the portion a (Z, by virtue of the resilience of the metal, springs inward, carrying with it. flat ortions d b and the exterior bends 4, 4. ach lateral portion connecting the bends 3, 4 is in the finished wall,- Fig. 9, composed now of short portions a c and d b whlch merge into the bends, and a third portion a at making an-angle with the planes of the former, and it is to the presence of this portion a d on 'the lateral portion conhereafter be advanced which are equally satisfactory. The portion .0 d corresponds to that particular part of the lateral wall which has been toughened and strengthened least,

as fully pointed out in the description of my application Sr. No. 366,207, filed April 3,

' 1907 ,'so that when the inner curved portion of the corrugation is forced into1thejmatrix roll and thus bent into a deeper and narrowershape, the tough arts of the wall tend to retain their origina shape while-the relatively weakportion. c d is calledupon to yield to the bending o eration, and is thus thrown into a lane lying at an angle to the portions (1 c, d Whether I am correct in this explanation of the causes involved in producing the result or not, the fact remains that my process, as herein set forth, never fails to produce-the desired result.

I' have alreadypointed out the desirability of having the flanges of the matrix roll shorter than the depth of the corrugation. This is desirable because if these flanges were made to bear against the outer curved portions 4, 4, while the die roll bears against the inner curved portion, thiswill set up a, tensile strain on the lateralwall which would draw the strains out of portion 0 (1, so that it would not s ring into the slanting position after die roli 8 is removed'from the corrugation. It is, however, not essential that the flanges of roll 9 should be shorter than the.de th of the corrugation, provided care is ta (en not to allow these flanges to bear strongly against the outer curved portions 4, 4, after the inner curved portion has been deepened andnarrowed by ie roll 8.

I may in the case of walls of small diameter, where the corrugations are necessarily shallow and hence the lateral walls are'nar rower, omit the straight portion a c and allow the angular portion 0 d to merge directly into the inner curved portion 3. This will tend to throw a greater bending movementupon the inner curvedportions 3, 3,, than upon the outer curved portions 4, 4 when the wall is expanded and collapsed as it should be, because the outer bends in a corrugated O fluid-pressure vessel are under greater strain than the inner bends. Iprefer, however, when the corrugations are deep enough to have present in the lateral portion both of the horizontal portions a c and d b.

While I have referred to the inner and 'outeriortions .of the corrugations as being. curve understood that the shape'of these is no part and have shown them as such,'it is of my present invention, and they may be formed any other way than that shown without departing from my invention. I.

much prefer,.however, that these parts of the corrugations should best-ruck on a curve, as

shown, for the reason that sharp angles are thereby avpiderbg'the presence of which would constitute lines of wear and tend to shortenthe life of the wall.

I have shown the corrugations here as lying in planes perpendicular to the axis of the wall. I much prefer this method of arranging the corrugations, but they may be made in the form of an ascending spiral similar to the threads of a screw, or otherwise, without departing from my invention.

What I claim is 1. A flexible corrugated tubular metal wall having lateral portions connecting the bends, each of said portions containing a flat portion merging into the bend and lying in a plane substantially normal to the axis of the said wall, and a portion making an obtuse angle with said flat portion and capable of bending through a greater angle than said flat portion when the wall is collapsed and expanded to relieve the strains at the curved portions of the corrugations.

2. A flexible corrugated tubular metal wall having lateral portions connecting the bends, each of said portions consisting of flat portions merging into alternate bends and lying in planes substantially normal to the axis of the said wall, and a portion conuectin 'said fiat portions mak ng angles with the latter and capable ofbending through a greater angle than said flat portions when the wall is expanded and collapsed to relieve, the strains at'the curved portions of the-corrugations.

3. A flexible corrugated cylindrical metal wall having lateral portions connecting the bends, each of said portions containing aflat portion merging into the bend d lying ma plane substantially normal to t e axis of the meeting said flat-portions-capable of bending through a greater angle than saidflat portions when "the wall is expanded andcollapsed to relieve the strains at the curved portions of the corrugations.

5. A flexible corrugated tubular metal wall having alternateconcave and convex portions connected to short lateral portions,-

said lateral portions being united by portions lying at an angle thereto. s

In testimony whereof I have signed this specification in the presence of two subscribing witnesses.

Witnesses: E. T. MANNING,

L. A PAINTER.

' WESTON M. FULTON. 

